Diacetone composition



Patented July 11, 1944 v UNITED STATES PATENT OFFICEDIACETOIZifiZZPOSITION Sophia 0. Williams, Chicago, 111.

No Drawing. Application March 5, 1941,

. Serial No. 381,895

8 Claims. (Cl. 252-73) This invention relates to a diacetone compositionand more particularly to a' diacetone composition which has beenstabilized against the effect of heat and cold.

This application is a continuation-in-part of my co-pending applicationsSerial'No. 298,693, filed October 9, 1939, and Serial No. 311,681, filedDecember 29, 1939.

Dlacetone (diacetone alcohol (cm) (OH') CHaCOCI-Is) is an inexpensiveorganic material of high boiling point, low freezing point, and moderateviscosity. When mixed with distilled water, it will produce a. lowfreezing mixture, but on mixture with ordinary tap water, thecomposition is unstable and tends to separate at temperatures slightlybelow 32 F. Moreover, the diacetone is unstable at high temperatures andbreaks down to give a variety of decomposition products includingacetone.

By means of the present invention diacetone is stabilized againstdecomposition at temperatures at least up to the boiling point of water,and furthermore diacetone-water mixtures are stabilized againstseparation at the freezing point .of water. a

This stabilization is accomplished by inclusion inthe diacetone systemof a buffering agent in sufficient quantity to produce a pH of 'notsubstantially more than 7.8 and preferably not below 4. The preferredrange of pH is between 5.2 and 6.8.

Any suitable buffering system may be employed which will produce abuffered system of reason able capacity in the ranges indicated.

The preferred system consists of a mixture of a poiycarboxylic acid andan alkali metal salt of a polyvalent acid within the specified pH rangeof 4 to 7.8. For example, a very eiilcient and inexpensive system may beprepared by combining citric acid and disodium phosphate in proportionssuitable for producing buffer mixtures of the above specified pH range.Similarly, metal salts of phthalic acid may be employed in combinationwith disodium phosphate or by themselves. Likewise, the system ofpotassium carbonate and butyric acid may be employed. although it ispreferred to use alpha hydroxy isobutyric acid in place of n-butyricacid. The butyric acidpotassium carbonate system, however, has lesscapacity as a buffer; and for this practical reason other bufler systemsof greater buffering capacity are preferred.

The following are examples of effective butlering systems. a

0.1 molal citric acid c.c 36.8 0.2 molal disodium phosphate c.c 63.2

The above mixture was added to diacetone at the ratio of 1 part of thebuffer to 3 parts of diacetone, and the mixture had a. pH of 6.42 atroom temperature. The temperature coefiicient of pH was negligible.

0.1 molal citric acid c,c 61.5 0.2 molal disodium phosphate c.c 38.5

This buifer was mixed with diacetone at the ratio of 1 part buffer to 3parts diacetone and the mix- -ture had a 'pH of 5.4.

III

0.27 molal potassium acid phthalate.. c.c 25 0.2033 molal NaOH c.c 0.20Water to make c.c; 100.00

This buffer solution was mixed with diacetone in the ratio of 1 partbuffer mixture to'3 parts diacetone, and produced a pH when mixed of5.59.

0.2 molal potassium acid phthalaten c.c-- 25 0.203 molal NaOH c.c 11.63Water to make c.c 100.00

c.c. of this buffer solution was mixed with 225 c.c. diacetone andproduced a pH of 7.8 which is approximately the upper limit forstability.

Lower pHs than those noted may be used, but tend to developpolymerization and other side reactions under certain conditions and,therefore, are preferably avoided.

j One of the'largest potential uses of the diacetone mixture is asanti-freeze solution and it is, therefore, preferred to use solutionsfairly close in pH to the neutral point. This effectively decreases thecorrosion of the metal parts which us When buffered as above described.diacetone- ,lution of diacetone may be diluted as desired.

Furthermore, other anti-freeze materials may be included, provided theyare compatible with diacetone. Glycerine is quite satisfactory used inthis manner.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom.

What I claim as new, and desire to secure by Letters Patent, is:

1. A composition of matter comprising an aqueous system includingdiacetone and a pH buffering agent in 'suflicient quantity to produce apH not substantially above 7.8.

2. A diacetone composition as set forth in claim 1, in which thebufierlng agent includes a polyvalent acid radical.

1, in which the. pH is maintained between 5.2

and 6.8.

5. An anti-freeze solution consisting essentialiv 02 diacetone andwater, and including a bufiering compound .of high capacity inproportion to produce a pH between 4.0 and 7.8

6. An aqueous diacetone composition having a pH between 4 and 7.8 andstabilized by the presence of a buifering agent including adiscarboxylic acid radical and a polyvalent acid radical.

7. An aqueous diacetone composition having a pH between 4 and 7.8 andstabilized by a buffering agent including citric acid and sodiumphosphate.

